ext4: add a function which sets up group blocks of a flex bg

This patch adds a function named setup_new_flex_group_blocks() which
sets up group blocks of a flex bg.

Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

2 files changed, 258 insertions, 0 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0e43bba049a9..05058e2b7f4f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -511,6 +511,14 @@ struct ext4_new_group_data {
         __u32 free_blocks_count;
 };
 
+/* Indexes used to index group tables in ext4_new_group_data */
+enum {
+        BLOCK_BITMAP = 0,       /* block bitmap */
+        INODE_BITMAP,           /* inode bitmap */
+        INODE_TABLE,            /* inode tables */
+        GROUP_TABLE_COUNT,
+};
+
 /*
  * Flags used by ext4_map_blocks()
  */
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 6076d5e4b513..e8ccb2f8f45b 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -234,6 +234,256 @@ static int extend_or_restart_transaction(handle_t *handle, int thresh)
 }
 
 /*
+ * set_flexbg_block_bitmap() mark @count blocks starting from @block used.
+ *
+ * Helper function for ext4_setup_new_group_blocks() which set .
+ *
+ * @sb: super block
+ * @handle: journal handle
+ * @flex_gd: flex group data
+ */
+static int set_flexbg_block_bitmap(struct super_block *sb, handle_t *handle,
+                        struct ext4_new_flex_group_data *flex_gd,
+                        ext4_fsblk_t block, ext4_group_t count)
+{
+        ext4_group_t count2;
+
+        ext4_debug("mark blocks [%llu/%u] used\n", block, count);
+        for (count2 = count; count > 0; count -= count2, block += count2) {
+                ext4_fsblk_t start;
+                struct buffer_head *bh;
+                ext4_group_t group;
+                int err;
+
+                ext4_get_group_no_and_offset(sb, block, &group, NULL);
+                start = ext4_group_first_block_no(sb, group);
+                group -= flex_gd->groups[0].group;
+
+                count2 = sb->s_blocksize * 8 - (block - start);
+                if (count2 > count)
+                        count2 = count;
+
+                if (flex_gd->bg_flags[group] & EXT4_BG_BLOCK_UNINIT) {
+                        BUG_ON(flex_gd->count > 1);
+                        continue;
+                }
+
+                err = extend_or_restart_transaction(handle, 1);
+                if (err)
+                        return err;
+
+                bh = sb_getblk(sb, flex_gd->groups[group].block_bitmap);
+                if (!bh)
+                        return -EIO;
+
+                err = ext4_journal_get_write_access(handle, bh);
+                if (err)
+                        return err;
+                ext4_debug("mark block bitmap %#04llx (+%llu/%u)\n", block,
+                           block - start, count2);
+                ext4_set_bits(bh->b_data, block - start, count2);
+
+                err = ext4_handle_dirty_metadata(handle, NULL, bh);
+                if (unlikely(err))
+                        return err;
+                brelse(bh);
+        }
+
+        return 0;
+}
+
+/*
+ * Set up the block and inode bitmaps, and the inode table for the new groups.
+ * This doesn't need to be part of the main transaction, since we are only
+ * changing blocks outside the actual filesystem.  We still do journaling to
+ * ensure the recovery is correct in case of a failure just after resize.
+ * If any part of this fails, we simply abort the resize.
+ *
+ * setup_new_flex_group_blocks handles a flex group as follow:
+ *  1. copy super block and GDT, and initialize group tables if necessary.
+ *     In this step, we only set bits in blocks bitmaps for blocks taken by
+ *     super block and GDT.
+ *  2. allocate group tables in block bitmaps, that is, set bits in block
+ *     bitmap for blocks taken by group tables.
+ */
+static int setup_new_flex_group_blocks(struct super_block *sb,
+                                struct ext4_new_flex_group_data *flex_gd)
+{
+        int group_table_count[] = {1, 1, EXT4_SB(sb)->s_itb_per_group};
+        ext4_fsblk_t start;
+        ext4_fsblk_t block;
+        struct ext4_sb_info *sbi = EXT4_SB(sb);
+        struct ext4_super_block *es = sbi->s_es;
+        struct ext4_new_group_data *group_data = flex_gd->groups;
+        __u16 *bg_flags = flex_gd->bg_flags;
+        handle_t *handle;
+        ext4_group_t group, count;
+        struct buffer_head *bh = NULL;
+        int reserved_gdb, i, j, err = 0, err2;
+
+        BUG_ON(!flex_gd->count || !group_data ||
+               group_data[0].group != sbi->s_groups_count);
+
+        reserved_gdb = le16_to_cpu(es->s_reserved_gdt_blocks);
+
+        /* This transaction may be extended/restarted along the way */
+        handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
+        if (IS_ERR(handle))
+                return PTR_ERR(handle);
+
+        group = group_data[0].group;
+        for (i = 0; i < flex_gd->count; i++, group++) {
+                unsigned long gdblocks;
+
+                gdblocks = ext4_bg_num_gdb(sb, group);
+                start = ext4_group_first_block_no(sb, group);
+
+                /* Copy all of the GDT blocks into the backup in this group */
+                for (j = 0, block = start + 1; j < gdblocks; j++, block++) {
+                        struct buffer_head *gdb;
+
+                        ext4_debug("update backup group %#04llx\n", block);
+                        err = extend_or_restart_transaction(handle, 1);
+                        if (err)
+                                goto out;
+
+                        gdb = sb_getblk(sb, block);
+                        if (!gdb) {
+                                err = -EIO;
+                                goto out;
+                        }
+
+                        err = ext4_journal_get_write_access(handle, gdb);
+                        if (err) {
+                                brelse(gdb);
+                                goto out;
+                        }
+                        memcpy(gdb->b_data, sbi->s_group_desc[j]->b_data,
+                               gdb->b_size);
+                        set_buffer_uptodate(gdb);
+
+                        err = ext4_handle_dirty_metadata(handle, NULL, gdb);
+                        if (unlikely(err)) {
+                                brelse(gdb);
+                                goto out;
+                        }
+                        brelse(gdb);
+                }
+
+                /* Zero out all of the reserved backup group descriptor
+                 * table blocks
+                 */
+                if (ext4_bg_has_super(sb, group)) {
+                        err = sb_issue_zeroout(sb, gdblocks + start + 1,
+                                        reserved_gdb, GFP_NOFS);
+                        if (err)
+                                goto out;
+                }
+
+                /* Initialize group tables of the grop @group */
+                if (!(bg_flags[i] & EXT4_BG_INODE_ZEROED))
+                        goto handle_bb;
+
+                /* Zero out all of the inode table blocks */
+                block = group_data[i].inode_table;
+                ext4_debug("clear inode table blocks %#04llx -> %#04lx\n",
+                           block, sbi->s_itb_per_group);
+                err = sb_issue_zeroout(sb, block, sbi->s_itb_per_group,
+                                       GFP_NOFS);
+                if (err)
+                        goto out;
+
+handle_bb:
+                if (bg_flags[i] & EXT4_BG_BLOCK_UNINIT)
+                        goto handle_ib;
+
+                /* Initialize block bitmap of the @group */
+                block = group_data[i].block_bitmap;
+                err = extend_or_restart_transaction(handle, 1);
+                if (err)
+                        goto out;
+
+                bh = bclean(handle, sb, block);
+                if (IS_ERR(bh)) {
+                        err = PTR_ERR(bh);
+                        goto out;
+                }
+                if (ext4_bg_has_super(sb, group)) {
+                        ext4_debug("mark backup superblock %#04llx (+0)\n",
+                                   start);
+                        ext4_set_bits(bh->b_data, 0, gdblocks + reserved_gdb +
+                                                     1);
+                }
+                ext4_mark_bitmap_end(group_data[i].blocks_count,
+                                     sb->s_blocksize * 8, bh->b_data);
+                err = ext4_handle_dirty_metadata(handle, NULL, bh);
+                if (err)
+                        goto out;
+                brelse(bh);
+
+handle_ib:
+                if (bg_flags[i] & EXT4_BG_INODE_UNINIT)
+                        continue;
+
+                /* Initialize inode bitmap of the @group */
+                block = group_data[i].inode_bitmap;
+                err = extend_or_restart_transaction(handle, 1);
+                if (err)
+                        goto out;
+                /* Mark unused entries in inode bitmap used */
+                bh = bclean(handle, sb, block);
+                if (IS_ERR(bh)) {
+                        err = PTR_ERR(bh);
+                        goto out;
+                }
+
+                ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb),
+                                     sb->s_blocksize * 8, bh->b_data);
+                err = ext4_handle_dirty_metadata(handle, NULL, bh);
+                if (err)
+                        goto out;
+                brelse(bh);
+        }
+        bh = NULL;
+
+        /* Mark group tables in block bitmap */
+        for (j = 0; j < GROUP_TABLE_COUNT; j++) {
+                count = group_table_count[j];
+                start = (&group_data[0].block_bitmap)[j];
+                block = start;
+                for (i = 1; i < flex_gd->count; i++) {
+                        block += group_table_count[j];
+                        if (block == (&group_data[i].block_bitmap)[j]) {
+                                count += group_table_count[j];
+                                continue;
+                        }
+                        err = set_flexbg_block_bitmap(sb, handle,
+                                                flex_gd, start, count);
+                        if (err)
+                                goto out;
+                        count = group_table_count[j];
+                        start = group_data[i].block_bitmap;
+                        block = start;
+                }
+
+                if (count) {
+                        err = set_flexbg_block_bitmap(sb, handle,
+                                                flex_gd, start, count);
+                        if (err)
+                                goto out;
+                }
+        }
+
+out:
+        brelse(bh);
+        err2 = ext4_journal_stop(handle);
+        if (err2 && !err)
+                err = err2;
+
+        return err;
+}
+
+/*
  * Set up the block and inode bitmaps, and the inode table for the new group.
  * This doesn't need to be part of the main transaction, since we are only
  * changing blocks outside the actual filesystem.  We still do journaling to